Commercial refrigeration and freezer units have condenser coils responsible for throwing off heat to the atmosphere that has been extracted from the chamber, holding the items intended to be refrigerated or frozen. To facilitate that heat exchange process, these coils, when contained within the appliance’s cabinet, airflow directly through their structure by a fan in the condensing unit. All matter of dust and debris are also drawn in with the air, potentially clogging the coils over time. Experts recommend frequent coil cleaning to ensure good airflow, often at periods of every 3-4 months as a minimum, and even more frequently in extremely dusty or dirty environments.
Condenser coils need frequent cleaning
Clogged coils cannot effectively throw off heat since the deposited dust/debris forms an undesired insulation layer. The refrigerant flowing through the unit gets too hot (resulting in high pressures), and begins damaging other components. The system draws higher amperage and increases run times. The refrigerant degrades, restricting flow and so forth.
As a result, a number of undesired things can happen, for instance:
Energy waste. Data from a field survey of coolers in San Francisco shows that the amount of energy needed to operate the appliance with clogged coils can increase by as much as 90-100%. At an electric rate of only $0.11/KwH, this translates to an average yearly electric waste of $432 per unit (or 3730 KwH). Multiply this by the number of refrigeration units in a given facility, and you get really big numbers into the several hundreds of dollars, often a lot more.
Malfunction of the unit. If the unit runs with clogged coils, you may face an emergency service call requiring removal of the refrigerant and teardown of the system. This can easily lead to 4-6 hours of labor plus part costs adding up to a significant bill. In extreme cases, the unit might need to be replaced.
Loss of product inventory. If the unit begins to malfunction, it may not be able to maintain the target temperature within the enclosure being cooled, leading to compromise of the integrity of the item(s) being refrigerated.
Shortening of the life of the unit. Malfunction of the appliance can also lead to a shortening of the useful life of the unit.
Safety issues for hydrocarbon refrigerant units.
There is a movement to replace hydrofluorocarbon refrigerants with “natural” refrigerants. One class of such refrigerant are hydrocarbons, such as propane (R-290). This type of refrigerant is highly flammable, and can be problematic in indoor locations unless certain safely measures are followed. It’s recommended that some R-290 refrigerant units need to have their condenser coils in a clean condition along with constantly running fans in the condenser coil area to promote good ventilation.
Cleaning condenser coils
Mere surface brushing and vacuuming of the condenser coil structure will remove the surface matting of dust/debris, but doesn’t get at the clogging within the interior of the structure..
Specialized coil cleaning brushes allow for extraction and removal by vacuuming of the deeply embedded dust/debris. Use of these implements greatly increases the time needed to get the cleaning job done.
For decades, knowledgeable technicians have resorted to the use of compressed air to quickly blow out clogged condenser coils, especially the deeply embedded material. However, doing this in indoor locations requires effective capture of the blown-off debris to ensure that no collateral contamination is caused.
Until recently, the technicians using compressed air coil cleaning have resorted to the use of a damp fabric or large garbage bag to catch the debris blown out of the coils. These primitive items both have serious deficiencies.
The damp fabric, which is applied to the side of the coil unit opposite the input of the compressed air, in many cases might not stay in place during the cleaning, causing undesired collateral pollution and further clean up. If it did remain in place, the technician has to contend with a thoroughly polluted, damp article requiring cleanup or disposal. The cleaning of a large number of units in a preventative maintenance scenario is not well served with the use of a damp fabric.
The use of a large garbage bag to catch the blown-off debris would require two technicians—one to hold the bag, the other to do the blowing. This method also can allow some of the blown-off debris to miss the open end of the bag being held. While a single operator can use this method, the bag needed to be taped or affixed to the coil structure slows down the cleaning operation.
More recently, there has been some movement toward better dust containment methods.
One example is an engineered dust containment that can be fitted over compatibly-sized coils in need of cleaning. The drawstring at the open mouth of the hood tightens once the bag is in place, forming a substantially sealed structure over the coils. The ports in the bag allow for the entry of a source of compressed air and vacuum, respectively, to blow out the clogged coils with the hood trapping the airborne debris until it is vacuumed out. The bag’s function is to merely trap the blown-off debris during the cleaning operation, not to collect it. Once the first unit is cleaned, the technician can remove the bag to use it on succeeding units.